Health Library

Depression(Major Depressive Affective Disorder; Unipolar Disorder; Unipolar Mood Disorder)

Depression is a mental illness marked by feelings of profound sadness and lack of interest in activities. It is a persistent low mood that interferes with the ability to function and appreciate things in life. It may cause a wide range of symptoms, both physical and emotional. It can last for weeks, months, or years. People with depression rarely recover without treatment.


The exact cause of depression is not known. It may be due to a certain type of brain chemistry. While the exact cause is not clearly established, factors that may play a role in depression include:

The Brain

Brain Man Face

Copyright © Nucleus Medical Media, Inc.

Risk Factors

Depression is more common in females. There are a range of factors that may increase your risk of depression. Examples include:

  • Having a family history of depression
  • Spouse with depression
  • Previous episode of depression
  • Hormonal changes
  • Chronic illness
  • Other conditions related to mental health such as anxiety , drug abuse , insomnia , and personality disorder
  • History of traumatic brain injury
  • History of concussion in teenagers
  • History of drug or alcohol abuse
  • Domestic violence
  • History of child abuse and neglect or sexual abuse
  • Obesity
  • History of bullying
  • History of self-harm as a teenager, with or without suicidal intent
  • Emotional or social factors, such as:
    • Little or no social support
    • Negative thought patterns and beliefs
    • Low self-esteem
    • Lack of personal control over circumstances
    • Feelings of helplessness

Depression can differ from person to person. Some people have only a few symptoms, while others have many.

Symptoms can change over time and may include:

  • Persistent feelings of sadness, anxiety, or emptiness
  • Hopelessness
  • Feeling guilty, worthless, or helpless
  • Feeling tired
  • Restlessness or irritability
  • Trouble sleeping, waking up too early, or oversleeping
  • Loss of interest in hobbies and activities
  • Trouble concentrating, remembering, or making decisions
  • Loss of interest in sex
  • Eating more or less than usual
  • Weight gain or weight loss
  • Thoughts of death or suicide with or without suicide attempts
  • Physical symptoms that defy standard diagnosis and do not respond well to medical treatments

There is no blood test or diagnostic test for depression. You will be asked about your symptoms and medical history, giving special attention to:

  • Alcohol and drug use
  • Thoughts of death or suicide
  • Family members who have or have had depression
  • Sleep patterns
  • Previous episodes of depression

Specific mental health exams may be done. This will help the doctor get detailed information about your speech, thoughts, memory, and mood. A physical exam and other tests can help rule out other causes.


Treatment may involve the use of medication and/or psychotherapy.

Severe depression can require hospital care, especially if you are at risk of hurting yourself or others.

Antidepressant Medications

Antidepressant medications may be most effective in people with severe depression. These medications can take 2-6 weeks to reach their maximum effectiveness. There are many different types of medications to treat depression. You will work with your doctor to find the medication that benefits you the most and has the least side effects.


Psychotherapy for depression consists of various types of counseling. These include cognitive-behavior therapy (CBT) , interpersonal therapy, psychodynamic therapy, or a combination of these. Therapy is designed to help you cope with difficulties in relationships, change negative thinking and behavior patterns, and resolve difficult feelings.

Diet and Exercise
Dietary Changes

Research suggests that diets high in tryptophan and certain B vitamins may be helpful. There is also mixed evidence that omega-3 fatty acids may reduce symptoms.

If you want to take supplements or change your diet, talk to your doctor first.

Dietary Supplements and Herbal Therapy

The herb St. John's wort may be an effective alternative to standard medications with fewer side effects. However, St. John's wort may reduce the effectiveness of many drugs, such as antidepressants, birth control pills, blood thinners, and other medications. It is important that you talk to your doctor before trying any herb.

There is also some evidence that dehydroepiandrosterone (DHEA) , a hormone that is available as a dietary supplement, may help some people.


A regular exercise program has been shown to relieve some of the symptoms. It should play a large role in the overall management of depression.

Electroconvulsive Therapy (ECT)

ECT is the use of an electric stimulus to produce a generalized seizure. It may be used in people with severe or life-threatening depression. ECT is also used for people who cannot take or do not respond to medication. It is considered a safe and effective procedure.

Vagus Nerve Stimulation (VNS)

VNS is used as therapy for depression when multiple trials of medication do not work. A pacemaker-like device stimulates the vagus nerve in the neck.

Vagus Nerve

Vagus Nerve

Stimulation of the vagus nerve (yellow) at the neck is a depression therapy option.

Copyright © Nucleus Medical Media, Inc.

Transcranial Magnetic Stimulation (TMS)

TMS involves the application of low-frequency magnetic pulses to the brain. The change in electrical field stimulates nerves. There are a number of studies that show the benefits of TMS for the treatment of depression. It may be used if you have not gotten better with medications and psychotherapy.

Other Treatment Options
Bright Light Therapy

Your doctor may recommend bright light therapy. This involves being exposed to high levels of light from a special light box that has a screen on it.


Meditation may help to improve the symptoms of depression.


Strategies to reduce your chances of becoming depressed include:

  • Being aware of your personal risk factors
  • Having a psychiatric evaluation and psychotherapy if needed
  • Developing social supports
  • Learning stress management techniques
  • Exercising regularly
  • Not abusing alcohol or drugs
  • Getting adequate sleep, rest, and recreation
  • Eating healthy food, including fruits, vegetables , and whole grains


Depression and Bipolar Support Alliance

Mental Health America


Canadian Mental Health Association

Canadian Psychiatric Association


Antidepressant use in children, adolescents, and adults. US Food and Drug Administration website. Available at: Updated August 12, 2010. Accessed September 18, 2014.

Columbia University. Q&A on bright light therapy. Columbia University website. Available at: Accessed September 18, 2014.

Depression. EBSCO DynaMed website. Available at: Updated September 15, 2014. Accessed September 18, 2014.

Depression. Mental Health America website. Available at: Accessed September 18, 2014.

Depression (mild to moderate). EBSCO Natural and Alternative Treatments website. Available at: Updated August 2013. Accessed September 18, 2014.

Groves DA, Brown VJ. Vagal nerve stimulation: a review of its applications and potential mechanisms that mediate its clinical effects. Neurosci Biobehav Rev. 2005;29:493-500.

St. John's wort. EBSCO Natural and Alternative Treatments website. Available at: Updated August 2013. Accessed September 18, 2014.

St. John's wort and depression. National Center for Complementary and Alternative Medicine website. Available at: Updated September 2013. Accessed September 18, 2014.

St. John's wort for depression. EBSCO DynaMed website. Available at: Updated April 26, 2012. Accessed September 18, 2014.

What is depression? National Institute of Mental Health website. Available at: Accessed September 18, 2014.

12/16/2008 DynaMed's Systematic Literature Surveillance. Linde K, Berner M, Kriston L. St. John's wort for major depression. Cochrane Database Syst Rev. 2008;CD000448.

10/9/2009 DynaMed's Systematic Literature Surveillance. Sánchez-Villegas A, Delgado-Rodríguez M, Alonso A, et al. Association of the Mediterranean dietary pattern with the incidence of depression. Arch Gen Psychiatry. 2009;66:1090.

7/26/2010 DynaMed's Systematic Literature Surveillance. Lespérance F, Frasure-Smith N, St-André E, et al. The efficacy of omega-3 supplementation for major depression: a randomized controlled trial. J Clin Psychiatry. 2010 Jun 15 early online.

12/13/2010 DynaMed's Systematic Literature Surveillance. Britton WB, Haynes PL, Fridel KW, Bootzin RR. Polysomnographic and subjective profiles of sleep continuity before and after mindfulness-based cognitive therapy in partially remitted depression. Psychosom Med. 2010;72(6):539-548.

3/28/2011 DynaMed's Systematic Literature Surveillance. Barbui C, Cipriani A, Patel V, Ayuso-Mateos JL, van Ommeren M. Efficacy of antidepressants and benzodiazepines in minor depression: systematic review and meta-analysis. Br J Psychiatry. 2011;198:11-16, sup 1.

7/28/2011 DynaMed's Systematic Literature Surveillance. Jakobsen JC, Hansen JL, Simonsen E, Gluud C. The effect of adding psychodynamic therapy to antidepressants in patients with major depressive disorder. A systematic review of randomized clinical trials with meta-analyses and trial sequential analyses. J Affect Disord. 2011 Apr 16. [Epub ahead of print]

11/6/2014 DynaMed's Systematic Literature Surveillance Mars B, Heron J, et al. Clinical and social outcomes of adolescent self harm: Population based birth cohort study. 2014;349:g5954.

Last reviewed August 2014 by Michael Woods, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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